weird hissing sound!!!
Thread Starter
|
Elder User
Joined: Jan 2005
Posts: 529
Likes: 0
weird hissing sound!!!
lately after i turn off my bronco and i walk infront of it, i hear a noticable hissing sound coming from right about the trans cooler or radiator. it slowly goes away in about a minute or two, but it does go out everytime in about the same amount of time.
think it could just be something with my a/c? i've been running it everyday with this 100 degree weather daily.
or do you think its more serious like a small leak in the trans cooler or radiator? i don't detect any leaks though.
what do you guys think it is?
think it could just be something with my a/c? i've been running it everyday with this 100 degree weather daily.
or do you think its more serious like a small leak in the trans cooler or radiator? i don't detect any leaks though.
what do you guys think it is?
Senior User
Joined: Sep 2003
Posts: 257
Likes: 0
Check the radiator cap. When the coolent gets hot, it's volume increases. I'm sure you knew this, but anyway, if the coolent runs out of room in the radiator, there is a bypass line that brings it back to the resivoir. The added pressure on the radiator cap could be making the noise. Just an idea.
Posting Guru
Joined: Jan 2003
Posts: 1,388
Likes: 0
From: SE Texas
Yeah, changing the radiator cap every year is cheap insurance. IF the temp is getting that hot to overheat the radiator/ trans cooler, look at changing the thermostat, or at least cleaning the radiator and cooler. I get about 5 lbs. of debris behind mine each year that needs to be vacuumed out.
Senior User
Joined: Feb 2004
Posts: 180
Likes: 0
From: Newport News, VA
My 87 does the same thing after stopping and running the a/c. I just thought it was from the a/c system somehow, kinda cooling down or releasing pressure...it's been doing it since I bought it back in 99 and I've had no problems.
Lead Driver
Joined: Jul 2003
Posts: 7,406
Likes: 52
From: Wheatland, Mo
I had the same thing on my 85 FSB and now also with my 02' F150. But only when I run my A/C. I beleive it is the freon in the lines "pressuring down". (If that makes any sense). Thats why it takes a minute for the cold air to start when you first turn it on...needs to build up pressure and start flowing.
Senior User
Joined: Dec 2004
Posts: 107
Likes: 0
i agree with the posts above, i am pretty sure its the A/C system hissing. My 92 Bronco does that only when the A/C has been working for a long time. Its been hott here too and i hear it when the engine stops just for a few minutes. I was alarmed to when i first heard it but i put my ear to the condenser one day and figured that was it. I had my AC recharged 4 years ago and still blowing cold air .
Thread Starter
|
Elder User
Joined: Jan 2005
Posts: 529
Likes: 0
yea i checked it out and its not the radiator cap. its on the opposite side. i paid closer attention and its coming from a canister thing all the a/c tubes are coming from.
so this short hissing is normal huh. cool.
however, the temp is a little warmer than normal than usual, but again, its at least 90-100 degrees lately.
so this short hissing is normal huh. cool.
however, the temp is a little warmer than normal than usual, but again, its at least 90-100 degrees lately.
Trending Topics
Lead Driver
Joined: Jul 2003
Posts: 7,406
Likes: 52
From: Wheatland, Mo
Yea it will be warmer when you run the A/C...especially on the real hot days. It puts additional load on the engine.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Posting Guru
Joined: May 2002
Posts: 1,306
Likes: 0
From: Bryan/College Station
The noise you hear is the A/C system pressures equalizing. There is a high pressure side and a low pressure side. The Compressor builds the pressure and the orifice tube located in the evaporator inlet is the transition point of the low pressure side. With the compressor turned off, the pressures in the two sides of the system seek to balance themselves out.
P-man, your noise is most likely the diaphram in the brake booster leaking. I had a Bronco that did that.
Chris
P-man, your noise is most likely the diaphram in the brake booster leaking. I had a Bronco that did that.
Chris
Elder User
Joined: Jan 2005
Posts: 656
Likes: 1
From: Houston
don't know what it is, but it is exacly what is described. it hisses for about 15 to 20 seconds and gets less and less until it stops. Maybe it is the pressure of the fuel injectors. but in mine it is not the AC.
Cargo Master
Joined: Nov 2003
Posts: 2,000
Likes: 39
From: North Dakota
brokebronco is right on. It is the low and the high side balancing out. I tend to hear mine more when it is hotter outside. Yesterday it was 113* and it was really hissing. Going to be 115* today, so I am sure it will be hissing away again.
